After hanging up the phone, a smile on Jimmy's face just wouldn't go away. Dave, this guy, really didn't shy away from the macabre, first killing a taxi driver and then, probably worried about the repercussions, he targeted homeless people.
As long as the lab report comes out, coupled with the fact that Dave admitted today that the three guns were his and he had possessed them for at least half a year with no one else touching them, it could be legally inferred that he was also behind the previous cases.
Chuck's thinking was truly spot-on. He had dealt with two homeless homicide cases and immediately suspected they might be linked to the taxi case. It seems the old detective's Sixth Sense was indeed strong—this was experience that couldn't just be derived from books alone.
